This release – like Mageia 4.1 was in its time – is a respin of the Mageia 5 installation and Live ISO images, based on the Mageia 5 repository and incorporating all updates to allow for an up to date installation without the need to install almost a year and a half worth of updates. It is therefore recommended for new installations and upgrades from Mageia 4.
you are currently running Mageia 5 then there is no need to install
Mageia 5.1 as it is the same as your system, provided that updates have
Mageia 5.1 ships with many updated packages, including LibreOffice 4.4.7, Linux kernel 4.4.32, KDE4 4.14.5, GNOME 3.14.3 and countless other updates.
The full release notes and errata contain further details about the supported hardware. The important addition is that 5.1 can now be installed on NVMe
based drives. Mageia 5 and by extension, 5.1 will be supported until 3
months after Mageia 6 is released, full details can be seen here.